We present a study designed by Painter et al. (DPS 2000) to
search for evidence of aqueous alteration in the surface
material of solar system objects. Using VRI broadband
photometry, we will search for the presence of the 0.7 um
absorption feature (indicative of Fe-bearing hydrated
silicates) in KBOs and Centaurs. Vilas (Icarus 111, 1994)
found a strong correlation between the presence of the
0.7-um feature in low-albedo asteroids with solar-like
colors and the 3-um water of hydration feature, indicative
of phyllosilicates. Recent work by Howell et al. (LPSC,
2001) confirms that the presence of the 0.7 um feature in
low-albedo asteroids definitely indicates the presence of
the 3.0-um water of hydration absorption feature, suggesting
the action of aqueous alteration in asteroids. In addition,
Feierberg et al. (Icarus 63, 1985) showed that when the U -
B color difference is > 0.12 in ECAS photometry, the
3.0-um absorption feature is often present in low albedo
asteroids. Therefore, if the U-B color difference is >
0.12 and the 0.7-um feature is present in UBVRI reflectance
photometry, water of hydration is implied in KBOs and
Centaurs. We pursue these studies based on the mixed flat or
steeply reddened photometry of these objects: Water ice has
been identified in near-IR dark, flat spectra of some
Centaurs, providing a source for the action of aqueous
alteration. The complex collisional history proposed for
these objects suggests a potential source of heating that
would melt water ice, providing a mechanism for aqueous
alteration to occur.

Finally, we will use BVR photometry to determine the B-V and
V-R colors, as has been done by Tegler and Romanishin
(Nature, 407). We will compare our results with colors of
KBOs and Centaurs published in the literature.

This research was supported by the National Research Council
and the NASA Planetary Astronomy Program.